1. Field of the Invention
The present invention relates to a field of machines and more particularly to compressors of a vortex type.
2. Description of the Prior Art
A vortex compressor is known comprising a casing with an annular working channel having suction and discharge ports and a stripper seal is arranged in the channel between the ports. An impeller is mounted in the casing, a disc of the impeller having blades thereon to form a blade set and the stripper seal has an orifice for gas removal (see DE-A-2409184).
In this known design, gas, contained in the space between the blades is heated as it is compressed and is partially released from the stripper seal through the orifice. This reduces the undesirable transfer of hot gas from the compressor suction side to the discharge side and increases the machine efficiency. The gas is removed from the stripper seal back to the annular working channel through the orifice along a special pipeline to a zone of an intermediate pressure. Although this design reduces the harmful impact of ballast gas, it is not sufficient since hot gas under some intermediate pressure appears at the compressor suction side from the space between the blades.
Another vortex compressor is known comprising a casing in which are formed an annular working channel, suction and discharge ports communicating with the annular channel, a stripper seal arranged between the suction and discharge ports, an impeller mounted in the casing, a ring of blades, mounted on a disc of the impeller, is located in the annular working channel, and wherein the casing and stripper seal comprise regions having arched shapes, communicating therebetween and equidistant from the blade edges (see SU-A-328265).
In this latter design, ballast hot gas from the space between the blades is almost completely removed to the ambient air and excluded from the compression process in the compressor. This design provides a blowing effect which, owing to a specific arched shape and arrangement of the region, the hot gas in the space between the blades is replaced by cold gas entering from the atmosphere. Such blowing effect ensures an increase of the machine efficiency, reduction of the gas temperature at the suction side due to lack of replenishment by the ballast hot gas, raising the amount of compression at this stage and improvement of weight output.
In such design, the amount of blowing depends substantially on the size of the arched region. On the one hand, the reduction of an arched region results in incomplete blowing with all resulting consequences. On the other hand, although the increase of the arched region intensifies the blowing, it can be attained only by increasing a portion of the annular channel occupied by the stripper seal since the arc is arranged within the margins of this portion. This results in reduction of the remaining portion of the working channel wherein the compression takes place thereby reducing the efficiency of the compressor. Therefore, the efficiency of this design is limited by the blowing.
3. Summary of the Invention
It is an object of present invention to provide a vortex compressor combining two gas dynamic blowing processes, namely, a removal of hot gas from a stripper seal, and a suction, and thereby to intensify the flow at the vortex compressor input and to extend a zone of an efficient compression process in an annular working channel, and thus, to raise the efficiency of the vortex compressor.
The object is attained by providing a vortex compressor for compressing a fluid and comprising a casing having an annular working channel adapted to have fluid compressed therein. A blade set having a plurality of blades rotatably mounted in the casing is provided and adapted to compress fluid in the channel. The compressor includes an inlet for the channel disposed radially inward of the blade set, an outlet for the channel disposed radially outward of the blade set, a two-piece stripper seal arranged in the channel and having a first radially inward member and a second radially outward member, in which the first and second members of the stripper seal are circumferentially offset from each other. The inlet and outlet of the compressor being circumferentially offset from each other, the radially outward member of the stripper seal being circumferentially closer to the outlet than the radially inward member of the stripper seal and the radially inward member of the stripper seal being circumferentially closer to the inlet than the radially outward member of the stripper seal. The stripper seal has an orifice for fluid removal, whereby fluid introduced into the inlet of the channel is compressed and emitted from the outlet of the channel and the orifice of the stripper seal.
Alternatively, a vortex compressor can be provided wherein the members of the stripper seal are two concentric annular members, the radially outward member being shorter than the radially inward member circumferentially along the annular channel.
Alternatively, a vortex compressor can be provided wherein the inlet of the channel is disposed adjacent an edge of the radially inward member of the stripper seal and the radially outward member of the stripper seal is circumferentially offset towards the other edge of the radially inward member.
Further a vortex compressor can be provided wherein the orifice of the stripper seal has a length in the circumferential direction of the channel longer than the combined length of the inlet and the radially inward member of the stripper seal and at least a portion of the inlet of the channel lies along a common radius with the orifice of the stripper seal.
Alternatively, a vortex compressor can be provided with a baffle arranged in the working annular channel at an end of the orifice of the stripper seal for removing compressed fluid more efficiently.
The disclosed advantages of the present invention will become more apparent from further description of the preferred embodiment of the invention with references to the accompanying drawings.